Project Summary: The long-term objective of my propsed research is to develop the capacity to identify proteins involved in disease, and use this approach to identify targets for therapeutics. The goal of this career development award is to allow the candidate to become an independent investigator in neuropsychiatric translational research. To accomplish these goals, I am in need of additional training in neurobiology, bioinformatics, and methods in translational research including mouse models and clinical research. The Johns Hopkins School of Medicine will provide me with expert mentorship in all of these areas of training. My intention is to develop these skills by elucidating the pathogenesis of LRRK2-induced Parkinson's disease. Mutation in the leucine-rich repeat kinase-2 (LRRK2) gene is the most common known familial cause of Parkinson disease (PD) and also a cause of sporatic PD. In the first aim, I will use two strategies to identify protein interactors-the yeast two-hybrid system, and tandem affinity purification followed by mass spectrometry. Yeast two-hybrid system has already identified two proteins which we hypothesize are related to the pathogenesis of PD. In my second aim, I will determine the functional relevance of any of the interators identified in Aim 1. I will focus on cell toxicity assays, since ultimately neuronal cell death causes PD, kinase assays, since LRRK2's kinase activity has been shown to be directly related to neuronal toxicity, and ubiquitination assays, since interference with the proteasome has been linked to PD. In addition, we will use LRRK2 PD patient tissue to directly determine the relevance of the interactors to PD. In Aim 3, I will generate a mutant LRRK2 transgenic mouse model to study the phenotype and pahthological changes in these mice and determine the functional significance in vivo of the interactors identified in Aims 1 and 2. By applying these approaches we can potentially elucidate PD pathogenic pathways and provide targets for therapeutics. Relevance: Studying the familial forms of Parkinson's disease (PD) will likely contribute to understanding the pathogenesis of both familial and sporadic PD. This project should lead to identification of proteins involved in disease development and progression that could be used as targets for disease intervention.